之后跌如钢铁企业、钢铁加工企业、火力发电等污染大户
pp because the homopolymer pp temperature is higher than 0c, verybrittle, so many commercial pp materials are 1~4% ethylene randomcopolymer/higher proportion of ethylene content of the segmentcopolymer. copolymer type pp material has lower thermal distortiontemperature (100c), low transparency, low gloss&low rigidity,but has stronger impact strength. the strength of pp increases withthe increase of ethylene content.